Large commercial refrigerators with glass doors are commonly found in grocery stores and convenience stores where food and drinks are stored for access to customers.
FIGS. 1a and 1b (Prior Art) are, respectively a top plan, cutaway view and a perspective view of a conventional frame section. The frame section 10 includes an external member 12, an internal member 14 and a gasket 16 mounted to the external member 12 via a gasket support 18. An edge of a door panel (not shown) on the cold side of the refrigerator sits on the gasket 16 when the door is closed. An insulating element 20 is inserted between the external and internal members 12, 14. Thermal bridges are formed by material of the external and internal members 12, 14, for example metal, that surround the insulating element 20.
Refrigerator door frames must be sturdy in order to withstand frequent and sometimes careless opening and closing by customers. For that reason, refrigerator doors are commonly made of steel or aluminum. Because these materials are good thermal conductors, condensation on glass door panels is a significant problem.
Shop owners desire to keep their glass doors free of any fogging in order to allow customers to clearly see the products that are available on refrigerator shelves. A common solution to the condensation problem is to install cable heating elements 22 within an open space 24 within refrigerator door frames. While this solution is effective in preventing condensation, it is highly inefficient in terms of energy consumption. Given the opposite requirements of keeping the inside of the refrigerator cold while keeping the door frames warm, electrical energy waste is considerable.
Therefore, there is a need for improvements in the construction of refrigerator door frames that compensate for problems related to condensation and to waste of energy.